im currently saving for a build for my l98. ive found a set of heads and a cam that i think will work well for my daily driver formula. i have a couple questions for the pros here on thirdgen to answer if they can.

the cam is comps Xfi 252 ( still want good gas milage) and the heads are patriots freedom series 64cc 185cc.

im asking if this is a good combo for my 350. ive heard storys of bad cam and head combo that makes worse power ( due to compression ) than stock.

my goal is a fast fun daily driver while still making good gas milage. thanks for any input im still new to this thing but im learning slowly.

links to cam and heads.

cam http://www.jegs.com/i/Comp-Cams/249/...52#moreDetails

heads http://www.summitracing.com/parts/PAR-2169/

 

cam is a touch small IMO

I'd go one step higher if you really are concerned with mileage and daily driving
http://www.jegs.com/i/Comp-Cams/249/...oductId=757952

Make sure you get the OE hydr roller version and not the retrofit.. your block is already a roller block.

Heads a nice for that motor..springs are 'ok' for that cam but i'd like to see abit more pressure on them, such as patriots "Gold" springs. Maybe you can order from Patriot with those springs on them? Just a suggestion but those springs should work as is.
ALSO CHECK to see if those heads are 1206 intake port or not...that can limit your intake choices. I have heard in the past the patriot stuff was 1206 but not sure.

What intake are you putting on this? Modded TPI? Stock TPI? Both cams will work good with either but this setup will NEED full aftermarket base/runners to make it worth it. Stock TPI just cant flow enough to take advantage of the heads/cam. A aftermarket base and big tube runners will wake that motor up.

You will be ok with stock compression and that cam. I dont know of many heads/cam stock bottom end cars that are slower because of the compression. I know I helped tune a cam/heads L98 HSR motor that has the big 280xfi cam and it runs high 7's in the 1/8 mile so far with traction issues. Its faster than my bolt on LS1 Trans am.

If you put a HSR on that motor or miniram, you could even try the 268XFI cam. Will have some lope to it but be streetable enough to drive everyday and pass emissions here in Houston.

The heads can support a 383 to 6000 rpm, so you can feed a 350 to 6000+ easily. TPI cant get you there, but HSR/miniram will. Not sure what you are planning.

 

thanks for the reply,

right now i have a stock tpi but i was planning an hsr intake coversion soon but probably not until spring or even summer of next year this head and cam swap would be my christmas present to myself.

im running a stock stall on my 700-r4 im hoping this cam wont be too big for that. thank you for clearing my head of a bad (or mis-matched) head and cam set-up i now feel alot more confident on pressing the order button for both.

 

i should also ask would this setup raise my compression? would i need to run 93 octane?

 

No, its probably going to be lower because chances are you'll be replacing your stock gasket with a thicker one. Also those are aluminum heads, that can run (read:need) more compression than iron heads. You'll have zero reason to need 93 octane with that setup.

The stock head is 64cc, FYI.

 

Just check to make sure they are not 1206 ports on the intake before order, else that TPI base probably wont seal against it and neither will an HSR unless you get the base made with extra material around the ports that can be ported to 1206.

Stall stall should be fine with either 252-260 xfi cams, they arent real big. I have seen the 280 run on a stock stall but it may have been a vette or s10 converter that stalled in the 1800-2000 range compared to 1600 ish for stock fbodys. Either way it should have ran on both just fine.

EDIT: yes it will probably lower your compression depending on gasket size. Being that most stock L98's have pistons down in the hole between .02 and .025", you will want to run around .02-.03 gasket for best quench height but being a mild combo it can get away with thicker gaskets. I dont know of many like .020-.030 but GM had a .028" gasket and so did Mr Gasket I believe that should work good.

You can get aggressive with timing and run on 93 if you wanted but its not necessary and probably wont pick up all that much more power over 87-89 oct tunes. Every little bit helps however.

 

thanks for the info guys im so glad i wont need 93 octane. ill look into the port sizing or better yet ill just email patriot directly. thanks again.

 

hmmm... do i have to run beehive springs with the xfi line of cams?

 

Depends on the cam but really just need to match spring pressures to the rev range you intend to use. The larger XFI cams that pull more RPMs will need more spring pressure to control the valves. If you dont they will float or just not make power beyond a certain rpm.

Beehives are great for those kind of cam lobes but a good strong double spring can handle those lobes.

Now with the 252-260 cams, you dont really need as much pressure since they arent turning as high of an rpm.
I think those current patriot springs should handle those 2 cams to 5800 rpm, but much more than that I'd ask them to upgrade the springs to their gold or extreme gold springs if possible to be safe. Dont want too much spring pressure but never want too little. Those smaller cams shouldnt need to go beyond 5800 anyway, especially with TPI. The 260 may like a shift point near 6K with the HSR down the road, so abit more spring could be a good idea. I've seen the 268 cam float valves around 5800 with worn out beehives from a member on here, so more spring pressure becomes the issue around 5800

 

thanks again orr89Rocz. i also emailed patriot about the port size. i hope to hear from them soon. im really excited about this build.